The Experts below are selected from a list of 29997 Experts worldwide ranked by ideXlab platform
I. Dutta - One of the best experts on this subject based on the ideXlab platform.
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role of interfacial and matrix creep during thermal cycling of Continuous Fiber reinforced metal matrix composites
Acta Materialia, 2000Co-Authors: I. DuttaAbstract:Abstract A uni-dimensional micro-mechanical model for thermal cycling of Continuous Fiber reinforced metal–matrix composites is developed. The model treats the Fiber and matrix as thermo-elastic and thermo-elasto-plastic-creeping solids, respectively, and allows the operation of multiple matrix creep mechanisms at various stages of deformation through the use of unified creep laws. It also incorporates the effect of interfacial sliding by an interface-diffusion-controlled diffusional creep mechanism proposed earlier (Funn and Dutta, Acta mater. , 1999, 47 , 149). The results of thermal cycling simulations based on a graphite Fiber reinforced pure aluminum–matrix composite were compared with experimental data on a P100 graphite–6061 Al composite. The model successfully captured all the important features of the observed strain responses of the composite for different experimental conditions, such as the observed heating/cooling rate dependence, strain hysteresis, residual permanent strain at the end of a cycle, as well as both intrusion and protrusion of the Fiber-ends relative to the matrix at the completion of cycling. The analysis showed that the dominant deformation mechanism operative in the matrix changes continually during thermal cycling due to Continuous stress and temperature revision. Based on these results, a framework for the construction of a transient deformation mechanism map for thermal excursions of Continuous Fiber composites is proposed.
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Role of interfacial and matrix creep during thermal cycling of Continuous Fiber reinforced metal–matrix composites
Acta Materialia, 2000Co-Authors: I. DuttaAbstract:Abstract A uni-dimensional micro-mechanical model for thermal cycling of Continuous Fiber reinforced metal–matrix composites is developed. The model treats the Fiber and matrix as thermo-elastic and thermo-elasto-plastic-creeping solids, respectively, and allows the operation of multiple matrix creep mechanisms at various stages of deformation through the use of unified creep laws. It also incorporates the effect of interfacial sliding by an interface-diffusion-controlled diffusional creep mechanism proposed earlier (Funn and Dutta, Acta mater. , 1999, 47 , 149). The results of thermal cycling simulations based on a graphite Fiber reinforced pure aluminum–matrix composite were compared with experimental data on a P100 graphite–6061 Al composite. The model successfully captured all the important features of the observed strain responses of the composite for different experimental conditions, such as the observed heating/cooling rate dependence, strain hysteresis, residual permanent strain at the end of a cycle, as well as both intrusion and protrusion of the Fiber-ends relative to the matrix at the completion of cycling. The analysis showed that the dominant deformation mechanism operative in the matrix changes continually during thermal cycling due to Continuous stress and temperature revision. Based on these results, a framework for the construction of a transient deformation mechanism map for thermal excursions of Continuous Fiber composites is proposed.
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Role of interfacial sliding on the longitudinal creep response of Continuous Fiber reinforced metal-matrix composites
Materials Science and Engineering: A, 1999Co-Authors: R. Nagarajan, I. Dutta, J.v. Funn, M. EsmeleAbstract:Experiments have been conducted on a model single Ni Fiber reinforced Pb-matrix composite in order to detect the effect of interfacial sliding during creep under axial tension. This was achieved by separately measuring the axial Fiber and matrix strains during creep deformation. The Fiber and matrix were observed to strain differentially, this being accommodated by interfacial sliding near the ends of the Fiber where the interfacial shear stress is large. Prior work on single Fiber push-down creep of Ni Fiber-Pb matrix composites has shown that the interface slides by diffusional creep with a threshold stress (Bingham flow). Based on this constitutive law for interfacial sliding, a unidimensional micro-mechanical model for thermo-mechanical deformation of Continuous Fiber reinforced metal-matrix composites is developed. The results show that during tensile creep, interfacial sliding is typically confined to the extremities of the tensile sample, allowing the isostrain condition to be valid over the tested gauge length. However, with increasing Fiber diameter and decreasing gauge length, significant interfacial shear stresses may develop well away from the extremities of the sample, allowing differential matrix and Fiber strains (and hence interfacial sliding) even within the gauge length. When interfacial sliding occurs within the gauge length, the composite creep rate is finite even after long times, whereas in the absence of interfacial sliding, the composite creep rate Continuously decreases and eventually vanishes with time. These effects are considered to be of particular importance during deformation in the absence of end-constraints, e.g. during thermal cycling or flexural creep of composites.
K.-h. Schwalbe - One of the best experts on this subject based on the ideXlab platform.
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Local strain fields and global plastic response of Continuous Fiber reinforced metal-matrix composites under transverse loading
Computational Materials Science, 1998Co-Authors: M. Werwer, A. Cornec, K.-h. SchwalbeAbstract:Abstract The influence of Fiber arrangement on the local plastic strain fields and the resulting mechanical response of Continuous Fiber reinforced metal-matrix composites under transverse loading has been studied systematically by means of finite element analyses. Random, hexagonal and square Fiber arrangements were investigated. The composite material examined consisted of isotropic linear-elastic Fibers which are perfectly bonded with an isotropic elastic–plastic matrix with power-law hardening behavior. The random arrangements were analyzed with representative material elements containing approximately 50 Fibers. The internal strain fields are highly influenced by the Fiber arrangements. Three different strengthening mechanisms are proposed for composites with perfectly plastic matrix material: the orientation, bowing-out and bending mechanisms. Simple analytical estimates are given for the orientation and the bending mechanisms. The influence of matrix work-hardening is explained by means of an effective deformable matrix volume fraction.
John W. Holmes - One of the best experts on this subject based on the ideXlab platform.
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Effect of loading rate on the monotonic tensile behavior of Continuous-Fiber-reinforced glass-ceramic matrix composit
Journal of the American Ceramic Society, 1996Co-Authors: Bent F. Sørensen, John W. HolmesAbstract:The stress-strain behavior of a Continuous-Fiber-reinforced ceramic matrix composite has been measured over a wide range of loading rates (0.01 to 500 MPa/s). It was found that the loading rate has a strong effect on almost every feature of the stress-strain curve: the proportionality stress, the composite strength and failure strain increase with increasing loading rate. The microstructural damage varies also with the loading rate; with increasing loading rate, the average matrix crack spacing increases and the average Fiber pullout length decreases. Using simple models, it is suggested that these phenomena are caused partly by time-dependent matrix cracking (due to stress corrosion) and partly by an increasing interfacial shear stress with loading rate.
M. Werwer - One of the best experts on this subject based on the ideXlab platform.
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Local strain fields and global plastic response of Continuous Fiber reinforced metal-matrix composites under transverse loading
Computational Materials Science, 1998Co-Authors: M. Werwer, A. Cornec, K.-h. SchwalbeAbstract:Abstract The influence of Fiber arrangement on the local plastic strain fields and the resulting mechanical response of Continuous Fiber reinforced metal-matrix composites under transverse loading has been studied systematically by means of finite element analyses. Random, hexagonal and square Fiber arrangements were investigated. The composite material examined consisted of isotropic linear-elastic Fibers which are perfectly bonded with an isotropic elastic–plastic matrix with power-law hardening behavior. The random arrangements were analyzed with representative material elements containing approximately 50 Fibers. The internal strain fields are highly influenced by the Fiber arrangements. Three different strengthening mechanisms are proposed for composites with perfectly plastic matrix material: the orientation, bowing-out and bending mechanisms. Simple analytical estimates are given for the orientation and the bending mechanisms. The influence of matrix work-hardening is explained by means of an effective deformable matrix volume fraction.
Bent F. Sørensen - One of the best experts on this subject based on the ideXlab platform.
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Effect of loading rate on the monotonic tensile behavior of Continuous-Fiber-reinforced glass-ceramic matrix composit
Journal of the American Ceramic Society, 1996Co-Authors: Bent F. Sørensen, John W. HolmesAbstract:The stress-strain behavior of a Continuous-Fiber-reinforced ceramic matrix composite has been measured over a wide range of loading rates (0.01 to 500 MPa/s). It was found that the loading rate has a strong effect on almost every feature of the stress-strain curve: the proportionality stress, the composite strength and failure strain increase with increasing loading rate. The microstructural damage varies also with the loading rate; with increasing loading rate, the average matrix crack spacing increases and the average Fiber pullout length decreases. Using simple models, it is suggested that these phenomena are caused partly by time-dependent matrix cracking (due to stress corrosion) and partly by an increasing interfacial shear stress with loading rate.